UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


                                  SCHEDULE 13D
                    INFORMATION TO BE INCLUDED IN STATEMENTS
                         FILED PURSUANT TO RULE 13d-1(a)

Chiron Corporation
 ------------------------------------------------ 
(Name of Issuer) 

Common Stock, $0.01 par value
 ------------------------------------------------ 
(Title of Class of Securities) 


170040109 
------------------------------------------------
 (CUSIP Number) 

Michael Rosenbaum
CAM North America, LLC
399 Park Avenue
New York, NY 10043
212-559-3627
------------------------------------------------ 
(Name, Address and Telephone Number of Person Authorized to Receive Notices and 
Communications) 

January 25, 2006
 ------------------------------------------------ 
(Date of Event which Requires Filing of this Statement) 

If the filing person has previously filed a statement on Schedule 13G to report 
the acquisition that is the subject of this Schedule 13D, and is filing this 
schedule because of Rule 240.13d-1(b)(e), 240.13d-1(f) or 240.13d-1(g) check the
following box [X]. 

NOTE: Schedules filed in paper format shall include a signed original and five 
copies of the schedule, including all exhibits. See Rule 240.13d-7(b) for other 
parties to whom copies are to be sent.

*The remainder of this cover page shall be filled out for a reporting person's 
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter 
disclosures provided in a prior cover page. 

The information required on the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 
1934 ("Act") or otherwise subject to the liabilities of that section of the Act 
but shall be subject to all other provisions of the Act(however, see the Notes).


SCHEDULE 13D 

CUSIP NO. 170040109  

1. Name Of Reporting Person: CAM North America, LLC  
     Tax Identification No: 01-0846058

2. Check The Appropriate Box If A Member Of A Group 
(a)    [X] 
(b)    [   ] 

3. Sec Use Only 

4. Source Of Funds:  OO

5. Check Box If Disclosure Of Legal Proceedings Is Required Pursuant To Items 
2(d) or 2(e): [  ] 

6. Place Of Organization:  Delaware


Number of shares beneficially owned by Reporting Person with:

7. Sole Voting Power:   - 0 -

8. Shared Voting Power Beneficially:  13,516,345

9. Sole Dispositive Power:  - 0 -

10. Shared Dispositive Power: 14,356,145

 
11. Aggregate Amount Beneficially Owned By Reporting Person: 14,356,145

12. Check Box If The Aggregate Amount In Row (11) Excludes Certain Shares: [  ]

13. Percent Of Class Represented By Amount In Row (11): 7.61% 

14. Type Of Reporting Person:  IA
 ----------------------------------------------------------------------------- 

SCHEDULE 13D 

CUSIP NO. 170040109 

1. Name Of Reporting Person: Smith Barney Fund Management LLC  
    Tax Identification No: 13-2616913

2. Check The Appropriate Box If A Member Of A Group 
(a)    [X] 
(b)    [   ] 

3. Sec Use Only 

4. Source Of Funds:  OO

5. Check Box If Disclosure Of Legal Proceedings Is Required Pursuant To Items 
2(d) or 2(e): [  ] 

6.  Place Of Organization:  Delaware


Number of shares beneficially owned by Reporting Person with:

7.     Sole Voting Power:   - 0 -

8.     Shared Voting Power Beneficially:  8,773,465

9.     Sole Dispositive Power:  - 0 -

10.    Shared Dispositive Power: 8,773,465
 

11. Aggregate Amount Beneficially Owned By Reporting Person: 8,773,465

12. Check Box If The Aggregate Amount In Row (11) Excludes Certain Shares [  ] 

13. Percent Of Class Represented By Amount In Row (11): 4.65%

14. Type Of Reporting Person: IA
 ----------------------------------------------------------------------------- 
 
SCHEDULE 13D 

CUSIP NO. 170040109  

1. Name Of Reporting Person: Salomon Brothers Asset Management Inc  
    Tax Identification No: 13-3440564

2. Check The Appropriate Box If A Member Of A Group* 
(a)    [X] 
(b)    [   ] 

3. Sec Use Only 

4. Source Of Funds:  OO

5. Check Box If Disclosure Of Legal Proceedings Is Required Pursuant To Items 
2(d) or 2(e): [  ] 

6. Place Of Organization:  Delaware


Number of shares beneficially owned by Reporting Person with:

7. Sole Voting Power: - 0 -

8. Shared Voting Power Beneficially:  96,247

9. Sole Dispositive Power: - 0 -

10. Shared Dispositive Power: 96,247
 

11. Aggregate Amount Beneficially Owned By Reporting Person: 96,247

12. Check Box If The Aggregate Amount In Row (11) Excludes Certain Shares: [  ]

13. Percent Of Class Represented By Amount In Row (11): 0.05% 

14. Type Of Reporting Person:  IA
 ----------------------------------------------------------------------------- 

ITEM 1. SECURITY AND ISSUER. 

This Schedule 13D relates to the Common Stock $0.01 par value 
(the "Common Stock") of Chiron Corporation, a Delaware corporation 
(the "Issuer"). The address of the principal executive offices of the Issuer is 
4560 Horton Street, Emeryville, CA 94608. 

ITEM 2. IDENTITY AND BACKGROUND. 

This statement is filed jointly by CAM North America, LLC ("CAM NA"), 
Smith Barney Fund Management LLC ("SBFM") and Salomon Brothers Asset Management 
Inc. ("SaBAM", and together with CAM NA and SBFM, the "Reporting Persons"). 
Each of CAM NA and SBFM is a Delaware limited liability company, and SaBAM is a 
Delaware corporation. Each of CAM NA, SBFM and SaBAM is a registered investment 
adviser under the Investment Advisers Act of 1940 ("Advisers Act") with its 
principal office located at 399 Park Avenue - 4th Floor, New York, NY 10043.  

Except as described below, none of the entities identified in this Item 2 has 
during the past five years been convicted in any criminal proceeding, nor been 
a party to a civil proceeding of a judicial or administrative body of competent
jurisdiction and as a result of such proceeding was or is subject to a judgment,
 decree or final order enjoining future violations of, or prohibiting or 
mandating activities subject to, federal or state securities laws or finding any
 violation with respect to such laws.

On May 31, 2005, the Securities and Exchange Commission (the "SEC") issued an 
order in connection with the settlement of an administrative proceeding against 
SBFM and Citigroup Global Markets, Inc. ("CGM") relating to the appointment of 
an affiliated transfer agent for the Smith Barney family of mutual funds 
(the "Smith Barney Funds").  At the time the order was issued, SBFM was an 
affiliate of CGM.

The SEC order finds that SBFM and CGM willfully violated Section 206(1) of the 
Advisers Act.  Specifically, the order finds that SBFM and CGM knowingly or 
recklessly failed to disclose to the Boards of the Smith Barney Funds in 1999 
when proposing a new transfer agent arrangement with an affiliated transfer 
agent that:  First Data Investors Services Group ("First Data"), the Smith 
Barney Funds' then-existing transfer agent, had offered to continue as transfer 
agent and do the same work for substantially less money than before; and that 
Citigroup Asset Management, then a Citigroup business unit that included the 
Smith Barney Funds' investment manager and other investment advisory companies, 
had entered into a side letter with First Data under which Citigroup Asset 
Management agreed to recommend the appointment of First Data as sub-transfer 
agent to the affiliated transfer agent in exchange, among other things, for a 
guarantee by First Data of specified amounts of asset management and investment
 banking 
fees to Citigroup Asset Management and CGM.  The order also finds that SBFM and 
CGM willfully violated Section 206(2) of the Advisers Act by virtue of the 
omissions discussed above and other misrepresentations and omissions in the 
materials provided to the Smith Barney Funds' Boards, including the failure to 
make clear that the affiliated transfer agent would earn a high profit for 
performing limited functions while First Data continued to perform almost all 
of the transfer agent functions, and the suggestion that the proposed 
arrangement was in the Smith Barney Funds' best interests and that no viable 
alternatives existed.  SBFM and CGM do not admit or deny any wrongdoing or 
liability. The settlement does not establish wrongdoing or liability for 
purposes of any other proceeding.  

The SEC censured SBFM and CGM and ordered them to cease and desist from 
violations of Sections 206(1) and 206(2) of the Advisers Act.  The order 
requires Citigroup to pay $208.1 million, including $109 million in disgorgement
 of profits, $19.1 million in interest, and a civil money penalty of $80 
million.  Approximately $24.4 million has already been paid to the Smith Barney 
Funds, primarily through fee waivers.  The remaining $183.7 million, including 
the penalty, has been paid to the U.S. Treasury and will be distributed pursuant
 to a plan to be prepared by Citigroup and submitted within 90 days of the entry
 of the order for approval by the SEC.  The order also requires that transfer 
agency fees received from the Smith Barney Funds since December 1, 2004 less 
certain expenses be placed in escrow and provides that a portion of such fees 
may be subsequently distributed in accordance with the terms of the order.

The order requires SBFM to recommend a new transfer agent contract to the 
Smith Barney Fund Boards within 180 days of the entry of the order; if a 
Citigroup affiliate submits a proposal to serve as transfer agent or 
sub-transfer agent, an independent monitor must be engaged at the expense of 
SBFM and CGM to oversee a competitive bidding process.  Under the order, 
Citigroup also must comply with an amended version of a vendor policy that 
Citigroup instituted in August 2004.  That policy, as amended, among other 
things, requires that when requested by a Smith Barney Fund Board, Citigroup 
Asset Management will retain at its own expense an independent consulting expert
 to advise and assist the Board on the selection of certain service providers 
affiliated with Citigroup.

ITEM 3. SOURCE AND AMOUNT OF FUNDS OR OTHER CONSIDERATION. 

The source of funds used for the purchase of the Issuer's securities were funds 
in certain investment advisory accounts managed by the Reporting Persons. 
The aggregate funds used by the Reporting Persons to make the purchases were 
$974,972,903.

ITEM 4. PURPOSE OF TRANSACTION.

The Reporting Persons have acquired the Issuer's Common Stock for investment 
purposes on behalf of certain investment advisory accounts, and such purchases 
have been made in the Reporting Persons' ordinary course of business as 
investment advisers. 

Depending on the Reporting Persons' assessment of future developments, one or 
more of the Reporting Persons may acquire additional securities of the Issuer or
may determine to sell or otherwise dispose of all or some holdings in the 
Issuer.

On November 25, 2005, the Issuer filed a Schedule 14A with the Commission 
regarding the acquisition by Novartis of all of the outstanding shares of the 
Issuer not already owned by Novartis at a price of $45 per share 
(the "Transaction"). 

On January 25, 2006, CAM NA, on behalf of itself and certain affiliated 
advisers, sent a letter (the "Letter") to Howard H. Pien, Chairman of the Board 
of Directors and Chief Executive Officer of the Issuer, stating that they 
believed the merger consideration of $45 in cash per Chiron share being 
offered by Novartis in the proposed Transaction is financially inadequate.  
The Letter further stated that CAM NA and such affiliated advisers intend to 
vote against the proposed Transaction. A copy of the Letter is attached as 
Exhibit B to this Schedule 13D and is incorporated herein by reference. 

The Reporting Persons may at any time reconsider and change their plans or 
proposals relating to the foregoing.

ITEM 5. INTEREST IN SECURITIES OF THE ISSUER 

(a) and (b). Set forth below is the beneficial ownership of shares of Common 
Stock of the Issuer for the Reporting Persons named in Item 2. 

As of the date hereof, CAM NA is the beneficial owner of 14,356,145 shares of 
Common Stock, representing approximately 7.61% of the Issuer's outstanding 
Common Stock, SBFM is the beneficial owner of 8,773,465 shares of Common Stock, 
representing approximately 4.65% of the Issuer's outstanding Common Stock, and 
SaBAM is the beneficial owner of 96,247 shares of Common Stock, representing 
approximately 0.05% of the Issuer's outstanding Common Stock.

All percentages set forth in this Schedule 13D are based upon the Issuer's 
reported 188,575,753 outstanding shares of Common Stock reported in the Issuer's
 Form 10-Q for the quarterly period ended September 30, 2005. 

(c) The following table sets forth the Reporting Persons' transactions in the 
shares of Common Stock of the Issuer during the sixty (60) days preceding the 
date of this report: 

Reporting Person        Date    Shares      Price       Transaction  
CAM NA                  11/25/2005       1,910  44.35      Open Market Sale
CAM NA                  11/28/2005       6,148  44.28      Open Market Sale
CAM NA                  11/29/2005       8,546  44.34      Open Market Sale
CAM NA                  11/30/2005       6,095  44.27      Open Market Sale
CAM NA                  11/30/2005       10     44.31      Open Market Purchase
CAM NA                  12/1/2005        8,791  44.33      Open Market Sale
CAM NA                  12/1/2005        15     44.31      Open Market Purchase
CAM NA                  12/2/2005        7,721  44.31      Open Market Sale
CAM NA                  12/2/2005        750    44.32      Open Market Purchase
SBFM                    12/2/2005        500    44.42      Open Market Purchase
CAM NA                  12/5/2005        6,533  44.32      Open Market Sale
CAM NA                  12/6/2005        11,227 44.50      Open Market Sale
CAM NA                  12/6/2005        120    44.49      Open Market Purchase
CAM NA                  12/7/2005        7,684  44.49      Open Market Sale
CAM NA                  12/8/2005        7,167  44.49      Open Market Sale
CAM NA                  12/8/2005        65     44.49      Open Market Purchase
CAM NA                  12/9/2005        8,302  44.51      Open Market Sale
CAM NA                  12/12/2005       7,656  44.54      Open Market Sale
CAM NA                  12/13/2005       12,635 44.58      Open Market Sale
CAM NA                  12/14/2005       20,957 44.59      Open Market Sale
CAM NA                  12/15/2005       15,456 44.68      Open Market Sale
CAM NA                  12/16/2005       8,457  44.79      Open Market Sale
CAM NA                  12/16/2005       2      44.68      Open Market Purchase
CAM NA                  12/19/2005       7,671  44.83      Open Market Sale
CAM NA                  12/20/2005       9,149  44.65      Open Market Sale
CAM NA                  12/21/2005       13,384 44.67      Open Market Sale
CAM NA                  12/22/2005       11,370 44.72      Open Market Sale
CAM NA                  12/22/2005       540    44.73      Open Market Purchase
CAM NA                  12/23/2005       5,977  44.63      Open Market Sale
CAM NA                  12/27/2005       9,600  44.60      Open Market Sale
CAM NA                  12/28/2005       13,551 44.64      Open Market Sale
CAM NA                  12/29/2005       13,845 44.55      Open Market Sale
CAM NA                  12/30/2005       5,917  44.42      Open Market Sale
CAM NA                  1/3/2006         9,298  44.63      Open Market Sale
CAM NA                  1/4/2006         9,964  44.69      Open Market Sale
CAM NA                  1/5/2006         7,644  44.62      Open Market Sale
CAM NA                  1/6/2006         6,100  44.70      Open Market Sale
CAM NA                  1/9/2006         6,380  44.71      Open Market Sale
CAM NA                  1/9/2006         250    44.73      Open Market Purchase
CAM NA                  1/10/2006        6,513  44.69      Open Market Sale
CAM NA                  1/11/2006        5,436  44.71      Open Market Sale
CAM NA                  1/12/2006        7,314  44.66      Open Market Sale
CAM NA                  1/13/2006        6,114  44.70      Open Market Sale
CAM NA                  1/17/2006        5,858  44.73      Open Market Sale
CAM NA                  1/18/2006        6,728  44.78      Open Market Sale
CAM NA                  1/18/2006        10     44.80      Open Market Purchase
CAM NA                  1/19/2006        7,030  44.80      Open Market Sale
CAM NA                  1/20/2006        6,111  44.74      Open Market Sale
CAM NA                  1/23/2006        8,818  44.72      Open Market Sale
        
                                
(d) and (e): Not applicable. 

ITEM 6. CONTRACTS, ARRANGEMENTS, UNDERSTANDINGS OR RELATIONSHIPS WITH RESPECT 
TO SECURITIES OF THE ISSUER 

Other than as described elsewhere in this Schedule 13D, the Reporting Persons 
have no understandings, arrangements, relationships or contracts relating to the
 Common Stock which are required to be described hereunder. 

ITEM 7. MATERIAL TO BE FILED AS EXHIBITS 

A) Joint Filing Agreement
B) Letter from CAM NA dated January 25, 2006 to the Issuer. 

SIGNATURES 

After reasonable inquiry and to the best of my knowledge and belief, 
I certify that the information set forth in this statement is true, complete and
correct. 
                                                
Date:  January 25, 2006

CAM North America, LLC

By:  /s/ George Shively
     George Shively, Secretary

Smith Barney Fund Management LLC

By:  /s/ Michael Kocur
     Michael Kocur, Assistant Secretary

Salomon Brothers Asset Management Inc


By:  /s/ George Shively
     George Shively, Secretary

                                   Exhibit A

                            JOINT FILING UNDERTAKING

This Joint Filing Agreement confirms the agreement by and among the undersigned 
parties that the Schedule 13D is being filed jointly on behalf of each of them 
with the Securities and Exchange Commission pursuant to Section 13(d) of the 
Securities Exchange Act of 1934, as amended.

Date:  January 25, 2006

CAM North America, LLC

By:  /s/ George Shively
     George Shively, Secretary

Smith Barney Fund Management LLC


By:  /s/ Michael Kocur
     Michael Kocur, Assistant Secretary


Salomon Brothers Asset Management Inc


By:  /s/ George Shively
     George Shively, Secretary

Exhibit B

LETTER

January 25, 2006

By Overnight Delivery

Mr. Howard H. Pien
Chairman of the Board and Chief Executive Officer
Chiron Corporation
4560 Horton Street
Emeryville, California 94608

Re:  Proposed Acquisition of Chiron Corporation By Novartis International AG

Dear Mr. Pien:

CAM North America, LLC and/or certain affiliated entities (collectively, "CAM") 
serve as adviser to various advisory clients that have been long-term 
shareholders of Chiron Corporation ("Chiron"), dating back to 1986.  Included 
among these clients is the Smith Barney Aggressive Growth Fund(.  Currently, 
certain of CAM's advisory clients' accounts own approximately 23,225,857 shares 
of Chiron common stock((, representing 12.32% of all Chiron common shares 
outstanding and 21.26% of the shares held by shareholders other than Novartis 
International AG ("Novartis").

As we have informed you previously, we believe the merger consideration offered 
by Novartis of $45 in cash per Chiron share is financially inadequate;
therefore, in keeping with our obligations to act in the best interest of 
clients, we cannot support this transaction and intend to vote against the 
proposed acquisition of Chiron by Novartis.  

Very truly yours,


Richard A. Freeman
Managing Director
CAM North America, LLC
        

cc:     Daniel L. Vasella, Chairman and Chief Executive Officer, Novartis
Raymund Breu, Director, Chiron 
Vaughn D. Bryson, Director, Chiron 
Lewis W. Coleman, Director, Chiron 
Pierre E. Douaze, Director, Chiron 
J. Richard Fredericks, Director, Chiron 
Paul L. Herrling, Director, Chiron 
Denise O'Leary, Director, Chiron 
Edward E. Penhoet, Director, Chiron 
Pieter J. Strijkert, Director, Chiron 



( Under a licensing agreement between Citigroup and Legg Mason, the names of 
funds, the names of any classes of shares of funds, and the names of investment 
advisers of funds, as well as all logos, trademarks and service marks related to
Citigroup or any of its affiliates ("Citi Marks") are licensed for use by Legg
Mason Citi Marks include, but are not limited to, "Smith Barney," "Salomon 
Brothers," "Citi," "Citigroup Asset Management," and "Davis Skaggs Investment 
Management," Legg Mason and its affiliates, as well as the fund's investment 
adviser, are not affiliated with Citigroup.

All Citi Marks are owned by Citigroup, and are licensed for use until no later
than one year after the date of the licensing agreement.

(( Of those shares, CAM has sole or shared voting power over at least 22,386,057
 shares.